Field of the Invention
The present invention is a balloon catheter for angioplasty procedures, comprising an elastic constraining structure mounted over the balloon where the structure has a mechanism of expansion to control the balloon inflation.
Conventional angioplasty balloons expand in an artery lesion at the least resistant areas of the lesion causing “dog bone” effect at the lesion ends and overexpansion in the softer areas, resulting in trauma to the vessel wall. Conventional angioplasty is associated with vessel displacement and its main mechanism of action is plaque compression where the vessel is significantly displaced or “pushed out” before reaction force can be generated and plaque compression takes place. During this process the balloon may expand in the axial direction (in addition to radial), a phenomenon that accelerates propagation of “cracks” in the vessel wall (dissections). This elongation continues after the balloon engages the lesion and the vessel wall and cause longitudinal stretch.
This mechanism of action causes a high rate of failure due to the vessel trauma (randomize studies in legs arteries document up to 40% acute failure rate and poor long term results with 20%-40% patency in one year). Attempts to modify the mechanism of action were mainly aimed at increasing the local force by adding cutting blades, wires or scoring elements that can penetrate into the vessel wall and create pre defined dissection plans. Those devices are used when encountering resistant lesions otherwise hard to crack open with conventional balloons. None of those technologies was designed to provide an alternative mechanism that leads to a gentler dilatation by minimizing vessel displacement and reducing the radial forces during balloon dilatation.